Low speed vibration

[Gorio]

Here I am sort of stumped. I have just crawl out from under the car to see if anyone has some ideas.
Vibration feels more in the chassis then the front end. It is very pronounced at 40 km/h or about 25 MPH.
There is some vibration thru a wide speed range about 30 km/h and up.
This is on a 1988 535i by the way so there is no flex disk which was the first thing to come to mind.
The u-joints are tight no play at all just like they should be. I did notice a little back lash in the diff. I am not sure how much would be considered normial?
The center bearing feels firm and is quiet but I haven’t gone as far as striping every thing back to have a look.
I don’t suspect it is the front end but check the bushings and ball joint anyway and all seems well up there.
I did notice I am in need of a rear axle seal at the diff. Anyone ever had a bearing go in the diff? I know sometimes the vibration takes out the seal.

Your thoughts and ideas are most welcome

[bmwrp8]

Here I am sort of stumped. I have just crawl out from under the car to see if anyone has some ideas.
Vibration feels more in the chassis then the front end. It is very pronounced at 40 km/h or about 25 MPH.
There is some vibration thru a wide speed range about 30 km/h and up.
This is on a 1988 535i by the way so there is no flex disk which was the first thing to come to mind.
The u-joints are tight no play at all just like they should be. I did notice a little back lash in the diff. I am not sure how much would be considered normial?
The center bearing feels firm and is quiet but I haven’t gone as far as striping every thing back to have a look.
I don’t suspect it is the front end but check the bushings and ball joint anyway and all seems well up there.
I did notice I am in need of a rear axle seal at the diff. Anyone ever had a bearing go in the diff? I know sometimes the vibration takes out the seal.

Your thoughts and ideas are most welcome
not sure about diff.bearing but check diff.oil and wheel bearing also. what about your tires?

[Ross]

A bearing will be noisy long before it starts vibrating. Half shafts is my guess. Or tires.

[BMWCCA1]

If it isn't tires I'd vote for transmission mounts, especially if it's an automatic. The early ones seem to not hold up well and then the drive-train isolation is more E28-like than E34.

[Gorio]

The tires have all been changed out and I am now in the process of trading the spare off around the car to eliminate the wheels as well. I have done the back with no change. I had looked at the tranny mounts while I was under there yesterday and they look good as new.
The half shaft is a possibility seeing one axel seal is leaking a bit could be from the vibration.
Wheel bears are all quiet and solid

Thanks for the ideas guys and please don't be afraid to suggest things I may have missed. It usually ends up being something simple.

[Gorio]

A bearing will be noisy long before it starts vibrating. Half shafts is my guess. Or tires.


Any easy way of checking them other then replacement?

[Gorio]

If I pull on the hand brake it increases the vibration.
The brakes are good and it was doing the same thing before I changed the rear rotors.

[Gorio]

I did find that the rear pitman arms (dog bones) are shoot. I have ordered replacements and will let you know what differance they make.
It looks likely that I will be dropping the drive shaft and taking to the machine shop.